The present invention relates to an air conditioning system including an outdoor unit that uses water as a heat source.
An air conditioning system using a water heat source includes an outdoor unit, which exchanges heat between water and refrigerant, and an indoor unit, which is connected to the outdoor unit. The air conditioning system further includes a refrigerant circuit formed by an indoor heat exchanger arranged in the indoor unit, an expansion valve, an outdoor heat exchanger arranged in the outdoor unit, and a compressor. During a cooling operation of the air conditioning system, the outdoor heat exchanger functions as a condenser and the indoor heat exchanger functions as an evaporator. The outdoor heat exchanger is for use with water. That is, the outdoor heat exchanger is cooled by water during a cooling operation of the air conditioning system.
When the air conditioning system performs a cooling operation, the temperature of the water flowing into the outdoor unit may become excessively low. In such a case, the outdoor heat exchanger may be overcooled. This would decrease the pressure difference between the high pressure and the low pressure in the outdoor unit, decrease the amount of refrigerant circulated through the refrigerant circuit, and lower the cooling capacity of the air conditioning system. Thus, an air conditioning system using a water heat source may employ a technique for limiting decreases in the water temperature during a cooling operation.
For example, the technique disclosed in Japanese Laid-Open Patent Publication No. 2001-304660 employs a water temperature adjusting means for adjusting the water temperature when a decrease in the water temperature causes the degree of superheating to be higher than a set value.